Differential effects of riboflavin and RRR-alpha-tocopheryl acetate on the survival of newborn RCS rats with inheritable retinal degeneration.

The dystrophic RCS rat is one of the most important animal models available for investigating retinal degeneration. In addition to the characteristic progressive loss of neural retina the strain is hampered by a high rate of mortality during the first week of life. Death rate during this period is greatly influenced by diet. A 69% reduction in mortality was achieved by supplementing a purified diet with double the amount of AIN-76 vitamin mix. The objective of this study was to identify vitamin(s) in the AIN-76 mix responsible for the enhanced survival. The experiment determined the effect on survival of independently doubling the concentration of each vitamin present in the AIN-76 vitamin mix. This was done by single addition of individual vitamins to a complete purified diet. Survival was determined in litters whose mothers and grandmothers had been provided the supplemented diets as their sole source of food. Supplementation with riboflavin increased mortality by 19%, whereas RRR-alpha-tocopheryl acetate supplementation reduced the mortality by 73%. The effect of RRR-alpha-tocopheryl acetate was equivalent to that achieved by supplementation with complete vitamin mix. First-week survival of pups (born alive) rose from 72.3% +/- 11.0 to 92.5% +/- 3.8 when the level of vitamin E was increased from 50 to 100 IU/kg diet.